View/Open

Year

Permanent link

Metadata

Appears in the following Collection

Abstract

Background: Reduced serotonergic neurotransmission is associated with impulsivity and negative affect in various psychiatric disorders. Research suggests that impulsivity and negative affect plays a prominent role in the etiology and maintenance of non-suicidal self-injury (NSSI). However, the relationship between serotonin and NSSI has currently received little research interest. The primary aim of the present study was to further delineate this relationship, by examining whether reduced serotonergic neurotransmission leads to heightened impulsivity and increased negative affect in adolescents who engage in NSSI.

Methods: Data were collected as part of the project “Repetitive non-suicidal self-injury: Impulsivity, executive control functions, and mentalization”. The authors participated in data collection. 32 adolescent females who had engaged in NSSI during the past twelve months participated in this between-subjects, double-blind experimental design. Participants were randomized into two groups. Half of the participants underwent acute tryptophan depletion (ATD), a method used to decrease serotonergic neurotransmission through ingestion of an amino acid mixture devoid of tryptophan – the dietary precursor of serotonin. The remaining participants were given a sham-depletion mixture containing tryptophan. Blood samples were drawn at baseline to measure plasma concentrations of tryptophan, together with administration of the Profile of Mood States (POMS). 4.5 hours after ingestion of the amino acid mixtures, when plasma concentration of tryptophan was expected to be at the lowest point, the second blood sample was drawn. Subsequently, the verbal and spatial subtasks of the Continuous Performance Test – Identical Pairs (CPT-IP) were administered, together with the second administration of POMS.

Results: Acute tryptophan depletion led to a 78.9 % fall in total plasma tryptophan levels. The intervention led to a significantly more impulsive response style and increased discriminative ability on verbal subtask of the CPT-IP. The intervention did not affect mood, suggesting that the effects of ATD on impulsivity are separate from effects on mood.

Conclusion: The results indicate that acute lowering of tryptophan increases impulsivity and discriminating ability in adolescents who engage in NSSI. The intervention did not affect mood. The findings suggest that NSSI are engaged in for affect regulating purposes.